There has recently been an increasing number of studies demonstrating the sensitivity of 2-[18F]-fluoro-2-deoxy-d-glucose positron emission tomography (FDG PET) in the management of differentiated and de-differentiated thyroid cancers. This prospective study was planned to investigate the value of FDG PET in the follow-up of patients with thyroid cancers. With this aim 36 patients (18 male, 18 female) with differentiated thyroid cancer who had either non-physiologic I-131 uptake outside the thyroid gland in whole body scanning, high Tg levels with negative whole body I-131 scanning, Tg antibody positivity, classified in high risk group or suspicious lesions with other imaging modalities were performed FDG PET imaging. Sensitivity, specificity, positive predictive value and negative predictive value in whole of the group were 54.5%, 92.8%, 92.3% and 56.5%, respectively. Sensitivity and specificity of FDG PET in the group with TSH levels of <2 μIU/ml were 66.6% and 100%, respectively, whereas these values were 40% and 87.5%, respectively in the group with TSH levels of >30 μIU/ml. These results show that FDG PET is a valuable test in the follow-up of patients with differentiated thyroid cancers.
Keywords: Fluor-18 fluorodeoxyglucose, positron emission tomography, thyroid cancer
